Could you please explain to me how we reached those conclusions? I mean which formula did we use for that

If (stock) return has mean of 10% and volatility of 20%, there is a 31% chance that your return next year will be negative

If (bond) return has mean of 6% and volatility of 10%, there is a 27% chance that you will be in the red next year

If (T-bill) return has mean of 3% and volatility of 3%, there is a 16% chance that you will be in the red next year